1. Field of the Invention
The present invention relates generally to a chip on board package for optical mice and lens cover for the same, and more particularly to a chip on board package for optical mice and lens cover for the same, in which a semiconductor chip of a package for optical mice is connected to circuit patterns on a board, and the circuit patterns are connected to a plurality of pins functioning as lead frames.
2. Description of the Prior Art
Generally, in semiconductor packages used for optical mice, a construction using lead frames is popularly used, which is depicted in FIG. 1. Referring to FIG. 1, a semiconductor chip 102 is attached to a die paddle 101. The die paddle 101 is electrically connected to lead frames 105 using fine gold, wires 103. In this case, the fine gold wires 103 are bonding wires. The die paddle 101 and some portion of each lead frame 105 are molded by epoxy molding compound 106, thus allowing their positions to be fixed. Then, a cavity 108 in which both the semiconductor chip 102 and the fine gold wires 103 are accommodated is enclosed with a cover 107. As described above, after the cavity 108 is enclosed, the lead frames 105 are adjusted to be mounted to a set (not shown) so as to form external terminals. In order to mount such a semiconductor package using lead frames to the set, via holes are formed in the set, and then leads are inserted into the via holes and soldered.
However, the package using lead frames is problematic in that it requires high initial investment cost so as to develop and produce lead frames, and molds must be managed continuously. Further, if lead frames in use must be changed, the same investment cost as that for previously used lead frames is inevitably required, thus preventing new products from being developed.
In order to overcome such problems, there is proposed a chip on board (COB) package not using lead frames as a typical semiconductor chip package. Such a COB semiconductor chip package is popularly used for supplementing disadvantages of the semiconductor chip package using lead frames. FIG. 2 shows a conventional COB package. Referring to FIG. 2, a semiconductor chip 202 is mounted on a board 201, and circuit patterns 204 are formed around the semiconductor chip 202 on the board 201. The circuit patterns 204 are extended to the bottom of the board 201 via the side surfaces of the board 201, thus enabling terminals 205 to be formed. Circuit patterns 204 are electrically connected to terminals of the semiconductor chip 202 by fine gold wires 203. In order to protect the semiconductor chip 202 and the fine gold wires 203, they are molded using epoxy resin. When the COB package is mounted on a set, the terminals 205 formed beneath the board 201 are directly-attached to the set through a soldering process, etc. Since the COB package does not use lead frames, it does not require high initial investment cost, it can cope with variations in products, and can decrease development time of new products.
However, there is difficulty in using the COB package as a semiconductor chip package for optical mice. That is, in order to allow light recognized by an optical mouse to reach a semiconductor chip through a lens, focus must be controlled by adjusting the height of the lens when the semiconductor chip is mounted on a set. However, if the conventional COB package is used, a board is directly mounted on the set, so the height of the package cannot be adjusted.
Further, as a mouse is used for various purposes, there are required mouse devices having various and complicated functions, compared with a conventional mouse. For this reason, the number of terminals of a semiconductor chip package is increasing compared with a conventional semiconductor chip package. Therefore, there is needed a new package product in which more terminals than those of a conventional package product can be formed.
Consequently, there is required a package for optical mice, which can be used as a lead frame package if necessary, having not only advantages of the COB package that initial investment cost is low, a development time of a product is short and application to development of various products is possible, but also advantages of the lead frame package that the focus of light can be controlled through a lens if the lead frame package is used for optical mice and additional terminals can be easily formed.
Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a semiconductor chip on board package for optical mice and lens cover for the same, which can simplify and facilitate a manufacturing process of a chip on board package, reduce initial investment cost thereof, reduce a development time thereof, and can easily cope with variations in products, by using a lens cover integrated with electrode pins.
Another object of the present invention is to provide a semiconductor chip on board package for optical mice and lens cover for the same, which can be used as a lead frame package when a semiconductor package is mounted on a set, and can have more terminals than those of a conventional chip on board package.
A further object of the present invention is to provide a semiconductor chip on board package for optical mice and lens cover for the same, in which central axes of both a lens and a semiconductor chip can easily correspond to each other when a board and a lens cover are assembled, and the lens cover has opened sides so as to combine several not-cut boards with lens covers, thus improving productivity of a semiconductor chip on board package.
In order to accomplish the above object, the present invention provides a semiconductor chip on board package for optical mice, comprising a board having top and bottom surfaces, and a pair of via holes formed along opposite side surfaces of the board to pass through the top and bottom surfaces; a semiconductor chip attached to a center portion on the top surface of the board and provided with a plurality of electrode terminals formed therein; at least one circuit pattern formed on the top surface of the board to be extended from the position to which the semiconductor chip of the board is attached, to positions in which the via holes are formed; at least one bonding wire for electrically connecting the electrode terminals of the semiconductor chip with the circuit pattern; and a lens cover for enclosing the top surface of the board, the lens cover having a lens disposed on the same axis as that of the semiconductor chip, a pair of electrode pins formed at positions of the lens cover corresponding to the positions of the pair of via holes in the board to be integrated with the lens cover, and an opening formed in a center portion within the lens cover for accommodating the semiconductor chip therein, wherein one end of each of the electrode pins of the lens cover is protruded downwardly from the bottom surface of the board through each via hole when the lens cover is combined with the board, and the electrode pins are bonded to the via holes of the board with solder, thus enabling the electrode pins to be electrically connected to the circuit pattern of the board.
Further, the present invention provides a semiconductor chip on board package for optical mice, comprising a board having top and bottom surfaces, and a plurality of via holes formed along opposite longer side surfaces of the board to pass through the top and bottom surfaces; a semiconductor chip arranged between the opposite via holes on the top surface of the board and provided with a plurality of electrode terminals formed therein; at least one circuit pattern formed on the top surface of the board to be extended from the position to which the semiconductor chip of the board is attached, to positions in which the via holes are formed; at least one bonding wire for electrically connecting the electrode terminals of the semiconductor chip with the circuit pattern; and a lens cover for enclosing the top surface of the board, the lens cover having a lens disposed on the same axis as that of the semiconductor chip, a plurality of electrode pins formed at positions of the lens cover corresponding to the positions of the via holes in the board to be integrated with the lens cover, and an opening formed in a center portion within the lens cover so as to prevent interference with the semiconductor chip, wherein one end of each of the electrode pins of the lens cover is protruded downwardly from the bottom surface of the board through each via hole when the lens cover is combined with the board, and the electrode pins are bonded to the via holes of the board with solder, thus enabling the electrode pins to be electrically connected to the circuit pattern of the board.
Further, the present invention provides a lens cover used for a chip on board package for optical mice, the lens cover enclosing a board, in which a semiconductor chip having a plurality of electrode terminals formed therein is attached to a top surface of the board, a plurality of via holes are formed along opposite longer side surfaces of the board to pass through the top and bottom surfaces, at least one circuit pattern is formed on the top surface of the board to be extended from the position to which the semiconductor chip is attached, to positions in which the via holes are formed, and the electrode terminals of the semiconductor chip are electrically connected to the circuit pattern by wire bonding wherein the lens cover encloses the top surface of the board and has a lens disposed on the same axis as that of the semiconductor chip, a plurality of electrode pins formed at positions of the lens cover corresponding to the positions of the via holes in the board to be integrated with the lens cover, and an opening formed in a center portion within the lens cover so as to prevent interference with the semiconductor chip, and one end of each of the electrode pins of the lens cover is protruded downwardly from the bottom surface of the board through each via hole when the lens cover is combined with the board, and the electrode pins are bonded to the via holes of the board with solder, thus enabling the electrode pins to be electrically connected to the circuit pattern of the board.